Motor-vehicle fuels of different compositions are sold alongside each other at filling stations. In particular, fuel mixtures comprising ethanol and gasoline are increasingly available, some of which may be used in conventional gasoline engines, while others may be used only in specially configured engines. E85, for instance, is a suitable fuel for so called flex-fuel vehicles: vehicles configured to run on widely varying fuel mixtures. Other mixtures, E10, for example, can be used in conventional gasoline engines so long as an appropriately homogenized mixture is provided.
However, some fuel distributors rely on splash blending during fuel transport to homogenize fuel mixtures. This method does not guarantee homogeneity and may result in a stratified mixture being supplied to the filling station. Thus, the mixture supplied to a customer's fuel tank may differ substantially from the expected composition. Moreover, stratification of a well-homogenized fuel mixture may occur on long standing in a vehicle's fuel tank as a result of repeated evaporation and condensation of fuel components. These factors may result in an inappropriately alcohol-rich fuel mixture being supplied to a gasoline engine not specially configured and/or controlled for alcohol-rich mixtures.
Further, vehicle fuel tank misfueling may be caused by simple, human error: a motorist or filling-station attendant may erroneously pump E85, for example, into a non-flex fuel vehicle. Results of misfueling may include degraded operation, e.g., stalling, difficulty starting, and rough idle. Further still, the misfueled motor vehicle may issue malfunction codes (MIL codes) that misdiagnose the problem. Misdiagnosis could trigger the servicing or replacement of non-defective, expensive parts, such as catalysts, fuel injectors, fuel pumps, exhaust gas oxygen sensors, or others. In addition, damage may occur to fuel-system or engine parts that are not resistant to high alcohol concentrations.
Finally, as alcohol-based fuels and alcohol-fueled vehicles become ever more common, the converse problem may arise: a vehicle designed to run on high-alcohol content fuel may be fueled erroneously with gasoline.
The inventors herein have recognized the above problems and have devised various solutions. For example, a method is provided to indicate improper fuel filling in a vehicle. In this method, an indicator is actuated if a proportion of alcohol in the fuel is outside a range of expected proportions. In some examples, the range corresponds to a non-flex fuel vehicle recommended range, or to an expected range for a low alcohol-content fuel, which may be between 0 and 15 percent alcohol by volume. The indicator may include a diagnostic code or a dash light. Further, the indicator may be actuated in combination with a mitigating action, which may involve adjustment of a fuel injector pulse width or an ignition spark timing, as examples.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.